Preheat the oven to 350°F (175°C) and grease a muffin tin or line with muffin liners.

In a mixing bowl, whisk together the flour, baking soda, and salt.

In another bowl, combine the mashed bananas, melted butter, beaten egg, brown sugar, and vanilla extract.

Pour the wet ingredients into the dry ingredients and mix until just combined.

Fold in the chocolate chips.

Divide the batter evenly among the muffin cups.

Bake for 18-20 minutes or until a toothpick inserted into the center comes out clean.

Allow to cool in the pan for a few minutes before transferring to a wire rack to cool completely.